Coating apparatus, coating method and coating-film forming appratus

ABSTRACT

A coating apparatus comprises a tray, a nozzle for supplying a coating liquid, and a squeegee which serves as an applicator for spreading a coating liquid. The tray has a recessed portion into which a substrate is placed, and a spinner chuck is provided in the recessed portion. In the spinner chuck, a chuck for attracting the substrate is attached to the upper end of a spinner shaft which can be lifted and lowered, and the upper surface of the chuck and the bottom surface of the recessed portion are arranged to be in the same plane in a state where the spinner shaft is lowered to the lowest position. The nozzle is positioned above a non-recessed portion of the tray and supplies a coating liquid only onto a non-recessed portion of the upper surface of the tray to form a coating liquid pool, and the applicator is relatively movable in a horizontal direction in a state of maintaining a certain distance with respect to the upper surface of the substrate accommodated into the recessed portion and spreads the coating liquid of the coating liquid pool from the non-recessed portion of the upper surface of the tray over the entire upper surface of the substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of prior U.S. patent applicationSer. No. 11/288,991 filed 29 Nov. 2005, now U.S. Pat. No. 7,611,581, andwhich claims priority under 35 USC 119 based on Japanese PatentApplication No. 2004-344819, filed 29 Nov. 2004. The subject matter ofeach of these priority documents is incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus and a method for applyinga coating liquid or a developing liquid on a surface of a substrate suchas a semiconductor wafer, a glass substrate, or the like so as to form acoating film or the like.

2. Description of Background Art

There have been known apparatuses disclosed in Documents 1-6 as anapparatus for forming a coating film having a uniform thickness on asurface of a substrate.

Document 1 has disclosed that a resist liquid is supplied with apredetermined width from a nozzle to a surface of a glass substrate, inwhich the nozzle is movable in a short side direction of the glasssubstrate, and the resist liquid supplied with a predetermined width isleveled to have a uniform thickness with a plate (squeegee) which movesin a long side direction of the glass substrate.

Document 2 has disclosed that a developing liquid is supplied from anozzle to a surface of a substrate which is horizontally spun by a spinchuck, and the developing liquid is applied onto the surface of thesubstrate to have a predetermined thickness while the developing liquidis received by a spreading member (squeegee) provided to keep a minutedistance from the surface of the substrate.

Documents 3 and 4 have disclosed that a substrate is placed into arecessed portion provided in a substrate stage so as to make the uppersurface of the substrate stage and the upper surface of the substrate inthe same plane, and a coating liquid is supplied from a slit nozzle tothe upper surface of the substrate stage including the substrate so asto form a coating film having a predetermined thickness on the surfaceof the substrate.

Document 5 has disclosed that while a tray having a recessed portion foraccommodating a substrate is transferred, a coating liquid is suppliedto a substrate placed in the recessed portion by using a slit nozzle, acoating film is formed by moving the substrate together with the tray,and thereafter the tray alone is moved to a cleaning station and adrying station.

Document 6 has disclosed that a pre-dispensing area is provided adjacentto a recessed portion for accommodating a substrate in a similar traystructure to Document 5.

-   [Document 1] Japanese Patent Application Publication No. 7-289973-   [Document 2] Japanese Patent Application Publication No. 8-022952-   [Document 3] Japanese Patent Application Publication No. 2001-269610-   [Document 4] Japanese Patent Application Publication No. 2002-59060-   [Document 5] Japanese Patent Application Publication No. 2003-245591-   [Document 6] Japanese Patent Application Publication No. 2004-209340

However, in the method as disclosed in Document 1, since the filmthickness becomes large at the starting point of the coating, it isimpossible to form a coating film entirely to the periphery of the glasssubstrate.

In the method as disclosed in Document 2, since the developing liquid isspread by spinning the substrate, the liquid moves toward the outside ofthe substrate and the amount of the liquid tends to be less in thecenter.

In the case of using a slit nozzle as in Document 3 and Document 4, itis difficult to supply a coating liquid with a uniform thickness in aside direction of the substrate. For example, if the width of the slitnozzle is larger in a longitudinal direction of the slit nozzle evenpartly, the coating liquid will be supplied excessively from that part.Also, if there is variation in the pressure during the coating by theslit nozzle, the amount of the supplied coating liquid will also bevaried. Thus, the structure of the slit nozzle requires delicateadjustment, which makes it difficult to handle.

Since Document 5 also uses a slit nozzle, its handing is difficult. Inaddition, this technique has a disadvantage in terms of space becausethe cleaning station and the drying station are separate from eachother. The technique disclosed in Document 6 has the same drawback as inDocument 5.

SUMMARY OF THE INVENTION

According to the present invention, there is provided a coatingapparatus including a rotatable tray having a recessed portion foraccommodating a substrate, a nozzle for supplying a coating liquid, andan applicator for spreading the coating liquid, wherein the recessedportion has a depth which allows an upper surface of a substrate and anupper surface of the tray to be in the same plane when the substrate isaccommodated into the recessed portion and the recessed portion has asimilar shape to the substrate, the nozzle for supplying a coatingliquid is positioned above a non-recessed portion of the tray, and theapplicator is relatively movable in a horizontal direction in a state ofmaintaining a certain distance with respect to the upper surface of thesubstrate accommodated into the recessed portion.

It is preferable that the applicator is a squeegee, a roller, or thelike. Also, in the recessed portion of the tray, it is possible toprovide a spinner chuck which can be lifted and lowered. Instead of thespinner chuck, a lifted and lowered pin may be provided.

According to the present invention, there is also provided a coatingmethod, which uses the above-mentioned coating apparatus, including thefollowing steps:

Step 1: placing a substrate into the recessed portion of the tray;

Step 2: supplying a coating liquid from the nozzle for supplying acoating liquid onto a non-recessed portion of the upper surface of thetray, and forming a coating liquid pool having an arc shape or a linearshape at an upstream side of the substrate with respect the movingdirection of the applicator as a reference by at least one of rotatingthe tray by a predetermined angle and moving the nozzle;

Step 3: spreading the coating liquid of the coating liquid pool onto theupper surface of the substrate by moving the applicator toward thesubstrate; and

Step 4: releasing the substrate from the recessed portion of the tray.

The method may further include the following steps:

Step 5: cleaning the tray by rotating the tray while a cleaning liquidis supplied to the upper surface of the tray from which the substratehas been released; and

Step 6: drying the tray by continuing tray rotation after the cleaningliquid is dispersed.

A coating film is formed by baking and drying the coating liquid afterstep 4. The structure of a coating-film forming apparatus may include asubstrate loader/unloader portion, a coating portion for a surface of asubstrate, a substrate heating portion, a cleaning portion for a rearsurface or an end surface of a substrate, and a robot for transferring asubstrate to and from each portion, in which the above-mentioned coatingapparatus may be used as the coating portion.

By providing the same rotatable tray as provided in the coating portionin the substrate heating portion and the cleaning portion, the transferby the robot can be performed efficiently.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 (a) is a plan view of a coating apparatus in a waiting state, andFIG. 1 (b) is a sectional view of the coating apparatus in a waitingstate;

FIG. 2 (a) is a plan view of a recessed portion of a tray in a statewhere a substrate is placed, and FIG. 2 (b) is a sectional view of therecessed portion of the tray in a state where a substrate is placed;

FIG. 3 (a) is a plan view showing a state where a coating liquid pool isformed on the upper surface of the tray, and FIG. 3 (b) is a sectionalview showing the state where a coating liquid pool is formed on theupper surface of the tray;

FIG. 4 (a) is a plan view showing a state where the coating liquid isleveled by a squeegee, and FIG. 4 (b) is a sectional view showing thestate where the coating liquid is leveled by a squeegee;

FIG. 5 (a) is a plan view showing a state where the coating liquid isdried by rotating the tray after the coating is finished, and FIG. 5 (b)is a sectional view showing the state where the coating liquid is driedby rotating the tray after the coating is finished;

FIG. 6 (a) is a plan view showing a state where the substrate is liftedfrom the tray, and FIG. 6 (b) is a sectional view showing the statewhere the substrate is lifted from the tray;

FIG. 7 (a) is a plan view showing a state where the tray is cleaned, andFIG. 7 (b) is a sectional view showing the state where the tray iscleaned;

FIGS. 8 (a) and (b) are the same view as FIG. 1 showing a state wherethe recovery is finished;

FIG. 9 (a) is a plan view of another embodiment of a coating apparatusand a coating method according to the present invention;

FIG. 9 (b) is a plan view of another embodiment of a coating apparatusand a coating method according to the present invention;

FIG. 9 (c) is a plan view of another embodiment of a coating apparatusand a coating method according to the present invention; and

FIG. 10 is a whole plan view of a coating-film forming apparatusaccording to the present invention.

DETAILED DESCRIPTION OF PRESENT EMBODIMENTS

Hereinafter, embodiments according to the present invention will beexplained with reference to the attached drawings. FIGS. 1-8 explain thepresent invention in the order of the processes. In each figure, (a) isa plan view and (b) is a sectional view.

The coating apparatus according to the present invention comprises atray 1, a nozzle for supplying a coating liquid 2, and a squeegee 3which serves as an applicator for spreading the coating liquid.

The tray 1 has a recessed portion 11 into which a substrate W is placed.The recessed portion 11 has a similar shape to the substrate W withrespect to the plan view. The depth of the recessed portion 11 issubstantially equal to the thickness of the substrate W.

A spinner chuck 12 is provided in the recessed portion 11. In thespinner chuck 12, a chuck 14 for attracting the substrate W is attachedto the upper end of a spinner shaft 13 which can be lifted and lowered,and the upper surface of the chuck 14 and the bottom surface of therecessed portion 11 are arranged to be in the same plane in a statewhere the spinner shaft 13 is lowered to the lowest position.

In the embodiment shown in the figure, the shape of the chuck 14 iscircular with respect to the plan view. However, the shape may berectangular, and it is possible to transmit the rotation of the spinnerchuck 13 directly to the tray 1 in this instance.

The nozzle for supplying a coating liquid 2 is positioned above anon-recessed portion of the tray 1. More specifically, in the presentembodiment, the nozzle 2 is positioned toward the squeegee side withrespect to the center of the tray 1.

The squeegee 3 has a rod shape, and the lower surface 3 a of thesqueegee is rounded. The squeegee 3 is movable back and forth toward thetray 1 by using a cylinder unit which is not shown in the figure. Whenthe squeegee 3 is positioned above the tray 1, a certain distance iskept between the lower surface 3 a of the squeegee 3 and the uppersurface of the substrate W, and the distance determines the thickness ofthe coating film.

The processes of applying a coating liquid to the substrate W by usingthe above-mentioned coating apparatus will be explained. The state shownin FIG. 1 is a waiting state, and firstly, the substrate W is placedinto the recessed portion 11 as shown in FIG. 2.

Next, a coating liquid such as a resist liquid is applied from thenozzle 2 to the upper surface of the tray 1, and the tray 1 is rotatedby the spinner shaft 13. The rotation angle is about 90-120°. Byrotating the tray 1, a coating liquid pool R is formed on the uppersurface of the tray 1 as shown in FIG. 3. In the present embodiment, thecoating liquid pool R is formed in front of the substrate W.

In order to form a coating liquid pool, it is also possible to move thenozzle 2. In this instance, when the movement course of the nozzle 2 isan arc shape, a similar pool to the above is formed. However, themovement course of the nozzle 2 may be a linear shape, or a pool may bediscontinuous.

Next, as shown in FIG. 4, the squeegee 3 is moved horizontally towardthe substrate W, so that the coating liquid of the coating liquid pool Ris spread on the upper surface of the substrate W by the lower surface 3a of the squeegee 3. Next, as shown in FIG. 5, after the coating isfinished, a uniform layer of the coating liquid formed on the substrateW is dried by rotating the tray 1.

After the layer of the coating liquid is dried, the spinner shaft 13 islifted and the substrate W is released from the recessed portion 11.With this, the coating film is automatically cut between the substrate Wand the recessed portion 11.

After the substrate W is released from the recessed portion 11, a nozzlefor supplying a cleaning liquid 4 is moved to be positioned above thetray 1, and a cleaning liquid is supplied onto the upper surface of thetray 1 while the nozzle for supplying a cleaning liquid 4 is moved backand forth as shown in FIG. 7. Also, the tray 1 is rotated so as toremove the coating liquid left on the tray 1. It is also possible toefficiently remove the coating liquid by applying an additional brush.Next, the tray 1 is dried by rotating, and the state shown in FIG. 8 isobtained. The state shown in FIG. 8 is the same state as the waitingstate shown in FIG. 1.

FIGS. 9 (a)-(c) are plan views of other embodiments of a coatingapparatus and a coating method according to the present invention. Inthe embodiment shown in FIG. 9 (a), the shape of the recessed portion 11is a rectangular shape with respect to the plan view, which correspondsto a glass substrate for liquid crystal.

In the embodiment shown in FIG. 9 (b), the intermediate area of thecoating liquid pool R is made larger than the other area so as tocompensate the shortage of the coating liquid in the central area.

In the embodiment shown in FIG. 9 (c), the shape of the squeegee 3 is anarc shape with respect to the plan view so as to gather the coatingliquid toward the center when the coating liquid is spread. However, theshape of the squeegee 3 is not limited to this, and an arc shape of thereverse direction may be used.

FIG. 10 is a whole plan view of a coating-film forming apparatusaccording to the present invention. The coating-film forming apparatuscomprises a robot 20 provided with an extendable arm, and aloader/unloader portion 21, a coating portion for a surface of asubstrate 22, a cleaning portion for a rear surface and an end surfaceof the substrate 23, and a substrate heating portion 24 which surroundthe robot 20. Also, in this embodiment, another tray 1 is provided inthe cleaning portion 23 and the heating portion 24, and a substrate istransferred by the robot 20 to each tray 1.

The loader/unloader portion 21 is comprised of a loader portion 21 a andan unloader portion 21 b. A loader portion for a substrate of adifferent size may be provided instead of the loader portion 21 a andthe unloader portion 21 b.

A cleaning portion 25 for the tray 1 is provided in the coating portion22, a liquid stock portion 26 is provided adjacent to the coatingportion 22, and an oven or a baking device is provided in the substrateheating portion 24. However, the substrate heating portion 24 may beprovided so as to be stacked on the cleaning portion 23.

In order to form a coating film such as a resist film by using thecoating-film forming apparatus, a layer of a coating liquid having auniform thickness formed on the substrate W is dried by rotating thetray 1 in the coating portion 22, the spinner shaft 13 is lifted, andthe substrate W is released from the recessed portion 11 of the tray 1.Next, the substrate W is received by a hand of the robot 20, transferredto the tray of the cleaning portion 23 so as to clean the edge surfaceand/or the rear surface, received by the hand of the robot 20 again,transferred to the heating portion 24, and finally a coating film isformed.

In the above-mentioned embodiment, “coating”, “drying by rotation”,“cleaning of the rear surface and/or the end surface”, and “baking oroven” are performed in this order. However, in a case where theviscosity of the coating liquid is low, the order of “coating”, “dryingby rotation”, “baking or oven”, and “cleaning of the rear surface and/orthe end surface” is also possible. If there is a step of drying byrotation, the substrate may stick to the tray, causing the substrate todeform when the substrate is released from the tray depending on thekind of the coating liquid. Therefore, it is possible to perform acoating-film forming method having no “drying by rotation” step andcomprising the steps of “coating”, “cleaning of the rear surface and/orthe end surface”, and “baking or oven”, or the steps of “coating”,“baking or oven”, and “cleaning of the rear surface and/or the endsurface”.

As is explained in the above, according to the present invention, it ispossible to easily level a coating liquid supplied onto a surface of asubstrate such as a semiconductor wafer and a glass substrate so as tohave a uniform thickness without any edge bead.

Also, according to the present invention, it is possible to greatlyreduce the amount of the wasted coating liquid compared to theconventional rotation coating technique.

Also, according to the present invention, since the structure is simplecompared to the conventional slit nozzle, no delicate adjustment isrequired to form a coating film having a uniform thickness.

In addition, according to the present invention, since the processesfrom coating to cleaning can be performed without moving the tray, it ispossible make the whole apparatus compact.

Also, since the above-mentioned coating apparatus is incorporated intothe coating-film forming apparatus according to the present invention,it is possible for the robot to efficiently conduct transfer of thesubstrate, and a single robot becomes sufficient as a transfer device byemploying the same tray in a heating device or a cleaning device.

Although there have been described what are the present exemplaryembodiments of the invention, it will be understood that variations andmodifications may be made thereto within the spirit and scope of theappended claims.

What is claimed is:
 1. A coating apparatus comprising: a rotatable trayhaving a recessed portion for accommodating a substrate and rotatabletogether with the substrate; a nozzle which supplies all of a coatingliquid for coating the substrate; and an applicator for spreading thecoating liquid, wherein the recessed portion has a depth which issubstantially the same as a thickness of the substrate so that an uppersurface of a substrate and an upper surface of the tray will be in thesame plane when the substrate is accommodated into the recessed portionand the recessed portion has a similar shape to the substrate, thenozzle for supplying a coating liquid is a tubular member with adischarge opening at a lower end thereof and is positionable above anon-recessed portion of the tray such that the nozzle supplies a coatingliquid only onto a non-recessed portion of the upper surface of the trayto form a coating liquid pool on the non-recessed portion of the tray,and the applicator is relatively movable in a horizontal direction in astate of maintaining a certain distance with respect to the uppersurface of the substrate accommodated into the recessed portion andspreads the coating liquid of the coating liquid pool from thenon-recessed portion of the upper surface of the tray over the entireupper surface of the substrate.
 2. The coating apparatus according toclaim 1, wherein the applicator is a squeegee or a roller and is movedlinearly in a direction parallel to a surface of the substrate when thesubstrate is in the recessed portion.
 3. The coating apparatus accordingto claim 1, further comprising a spinner chuck which can be lifted andlowered, and is provided in the recessed portion of the tray.
 4. Thecoating apparatus according to claim 1, wherein the applicator is asqueegee having an arc shape when viewed in plan.
 5. The coatingapparatus according to claim 1, wherein the nozzle forms the coatingliquid pool to have an arc shape or a linear shape adjacent a portion ofthe substrate at an upstream side of the substrate with respect themoving direction of the applicator as a reference by at least one ofrotating the tray by a predetermined angle and moving the nozzle.
 6. Thecoating apparatus according to claim 1, wherein the recessed portion ofthe tray has a size and shape which are substantially the same as thoseof the substrate such that, when the substrate is placed in the recessedportion, the substrate substantially completely fills the recessedportion when viewed in plan.
 7. The coating apparatus according to claim1, wherein the coating liquid pool on the non-recessed portion of thetray has a sufficient volume so that the applicator spreads the liquidover the entire surface of the substrate at a uniform thickness.
 8. Thecoating apparatus according to claim 1, wherein at least one of therotatable tray and the nozzle is moved relative to the other while thenozzle supplies the coating liquid to form the coating liquid pool. 9.The coating apparatus according to claim 1, wherein after the coatingliquid pool has been fully formed the applicator spreads the coatingliquid of the coating liquid pool from the non-recessed portion of theupper surface of the tray over the entire upper surface of thesubstrate.